What Is a One-Rep Max?
The squat max calculator turns a hard set of squats into an estimated one-rep max. Because the squat taxes the whole body, a true single is the most systemically fatiguing test in the gym — estimating from a set of five is both safer and nearly as accurate.
How the calculator works
You enter the heaviest weight you can lift for a clean set of 1–20 reps. The calculator runs three published formulas — Epley (weight × (1 + reps/30)), Brzycki (weight × 36/(37 − reps)) and Lombardi (weight × reps^0.10) — and averages them. Below the estimate you get a full training-percentage table from 50% to 95% with the typical rep target at each load.
Common use cases
- Setting training loads for 5/3/1, Texas Method or any percentage-based programme
- Testing progress without grinding out a true single
- Comparing strength across bodyweights with a training partner
- Planning peaking blocks around 90–95% loads
Formula & accuracy
All three formulas agree within a few percent below about 10 reps; above 10 reps estimates drift high because fatigue, not strength, starts limiting the set. For best results use a set of 3–6 reps at a weight you could not lift more than once more.
Enter the weight for competition-depth squats (hip crease below knee). High-bar and low-bar estimates can differ by 5–10%; use your main competition style.
Safety notes
Estimated maxes are not invitations to test a true single. Keep a spotter, warm up progressively, and leave one rep in reserve on heavy working sets.
Frequently Asked Questions
How accurate is a calculated one-rep max?
Within 2–5% of a tested 1RM when you use a hard set of 3–6 reps. Sets above 10 reps overestimate because muscular endurance becomes the limiter.
Which formula should I trust?
The calculator averages Epley, Brzycki and Lombardi. Epley is the most widely used; Brzycki tends to read slightly lower at higher rep counts.
How often should I retest?
Every 4–8 weeks is plenty for a working estimate — retesting too often adds fatigue without information.
Why is my squat max estimate lower than my deadlift?
The squat uses less total muscle mass and has a shorter range of leverage advantages — a deadlift 10–20% above your squat is typical.
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